The development of hyphal symbionts and pathogens relies on fatty acid biosynthesis by the plant host
A. KEYMER (1) (1) University of Munich (LMU), Germany

Many biotrophic filamentous microbes develop host membrane-surrounded hyphal structures, such as haustoria or arbuscules inside plant cells. The development of these putative feeding structures depends on a genetic program of the host plant that allow compatibility and mediates cellular rearrangement for intracellular accommodation of the hyphal structure. In a forward genetics screen designed to find Lotus japonicus mutants that are perturbed in arbuscular mycorrhiza development we identified the mutant disorganized arbuscules (dis) that is impaired in arbuscule branching. We combined classical mapping with next generation sequencing to identify the causative mutation. The DIS gene, encodes an enzyme involved in fatty acid elongation, of which three paralogs are present in the Lotus japonicus genome. Promoter-GUS localization showed that the DIS promoter is active in arbuscule containing cells. A DIS-YFP-fusion was targeted to plastids, consistent with the subcellular localization of fatty acid biosynthesis. The simultaneous presence of KASI gene related to housekeeping function and a symbiosis-related paralog (DIS) is conserved in AM-forming dicotyledons. In contrast, the genomes of eight plant species, which are unable to form AM, contain a single KASI gene. Interestingly, an kasI mutant of Arabidopsis thaliana impairs development and reproductive success of the biotrophic pathogens Hyaloperonospora arabidopsidis (oomycete) and Erysiphe cruciferarum (ascomycete). Taken together these data indicate that host fatty acid biosynthesis might be a critical compatibility factor for mutualistic and parasitic interactions of plants with biotrophic filamentous microbes.

Abstract Number: P1-6
Session Type: Poster